1. Field of Invention
This invention relates to the quantification of contaminants in soil and more particularly to a geophysical method for quantifying the volume of dense non-aqueous phase liquids in the subsurface.
2. Background of the Invention
Dense non-aqueous phase liquids (DNAPL) are common and highly problematic contaminants of concern in ground water. They are of concern at dissolved concentrations orders of magnitude lower than their solubility, they can migrate many meters vertically in soils within hours or days, they pool at horizontal porosity and permeability boundaries, and their migration is little effected by groundwater flow or gradients.
Quantifying the volume of non-aqueous phase liquids in the subsurface is difficult. To date, methods have been developed which can detect DNAPL in the subsurface but these methods are not effective in quantifying the amount of DNAPL present. As cleanup costs at DNAPL sites typically run in the millions of dollars, accurately quantifying the volume of DNAPL present is very important. There is a need for a method to locate and quantify the extent of organic contaminants in the non-aqueous phase in order to develop strategies to remediate the DNAPL sources. Site remediation is dependent upon reducing a certain percentage of the DNAPL contaminant mass that is the source for the dissolved contaminant plume. In order to estimate the amount of mass that needs to be removed, the percent saturation of DNAPL within the subsurface needs to be reasonably quantified.
Accordingly, what is needed in the art is a method that can directly detect and quantify the volume of DNAPL present in a saturated soil.
It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.